1. Field of the Invention
The invention relates to a test stand arrangement having a test specimen that is connected to at least one electric motor for driving and/or loading the test specimen, as well as having a control arrangement for the or each electric motor for driving and/or loading the test specimen.
2. The Prior Art
Rising fuel prices and statutory regulations with regard to emissions and CO2, combined with higher customer expectations with regard to comfort, are leading to a continually growing demand for cost-optimized vehicles with highly innovative drive trains. For this reason, vehicle manufacturers are confronted with the challenge of developing highly complex drive train solutions in a rapid and purposeful fashion. In order to meet this challenge, a wide array of strategies has been developed, with the “front loading” of the development process on the basis of the “road to lab math” strategy having crystallized as the core strategy. Here, development tasks that earlier could only be handled in expensive prototype environments are to be transferred into early process phases such as is described, for example, in Geschweitl K., Ellinger R., Loibner E, “Tools and Methods in the Hybrid Development Process” [“Werkzeuge and Methoden im Hybrid Entwicklungsprozess”], 19th “Engine and Environment” [“Motor und Umwelt”] conference, Graz, 2007, in Schyr C. and Geschweitl K.,“Methodical Validation of Hybrid Drive Trains” [“Methodische Validierung von hybriden Antriebsträngen”], 2nd International Development Methodology Symposium, Darmstadt, 2007, or in Seidl C., Rainer G., Schoeegl P., Martini E., Dener D., “Enabling Future Powertrain Solutions by Innovative Simulation & Testing Toolchains,” 32nd FISTIA World Automotive Congress, Munich, 2008. The prototype environments are to be replaced by simulation environments. However, this strategy presumes that integrated development environments are available to the developer in which he is able to take into account the overall system behavior of the vehicle as well as its interaction with its environment.
In many developments, an essential point is reproducing the behavior of a multi-mass flywheel, usually a dual-mass flywheel (ZMS), on the test stand, in particular an engine test stand. In the course of developing hybrid drive systems, the multi-mass flywheel, in particular the dual-mass flywheel, also becomes the core element for all drive trains because, along with the suitable functionality, it allows a good decoupling of the internal combustion engine and the drive train. Currently, it is possible to duplicate the actual behavior of a multi-mass flywheel only using real prototypes on a test stand. This caused dependence upon the availability of dual-mass flywheels. Examples of this may be found in publications such as Walter A., Kiencke U., Jones S., Winkler T.: “The multi-mass flywheel as a virtual sensor” [“Das Mehrmassenschwungrad als virtueller Sensor”]. MTZ June 2007, volume 68; Cavina N., Serra G.: “Analysis of a Dual Mass Flywheel System for Engine Control Applications” SAE 2004-01-3016; A. Walter, U. Kiencke, S. Jones and T. Winkler, “Anti-jerk & idle speed control with integrated sub-harmonic vibration compensation for vehicles with dual mass flywheels,” SAE, 2008, or in A. Walter, M. Murt, U. Kiencke, S. Jones and T. Winkler, “Compensation of sub-harmonic vibrations during engine idle by variable fuel injection control,” accepted for 17th IFAC World Congress, Seoul, South Korea, 2008.
However, in the case of electrical drive trains in the future, the demands on such modules for decoupling are rising. On the one hand, the fluctuations in torque are increasing and, on the other hand, the excitation frequency when the internal combustion engine is activated is decreasing. Moreover, the hybrid drive system allows and requires rapid activation and deactivation of the internal combustion engine when idling and during driving. Naturally, this should not cause any effect noticeable to the driver on the drive train or the vehicle, the shortest possible startup times should be achieved, in particular when the start is initiated by a request from the driver, adherence to all emissions regulations should be guaranteed even with a significantly increased number of startup processes and an altered warm-up behavior of the structure and exhaust system, and the accomplishment of “change of mind” scenarios is required, for example, restarting the internal combustion engine during parking. In current solutions having dual-mass flywheels, this restarting can cause damage.
The object of the present invention is therefore to provide a test stand, in particular a test stand for an internal combustion engine vehicle and/or a vehicle drive train that, while preventing the disadvantages elucidated above, is able to create the connection between the drive train and vehicle simulation and the real-world, vehicle-specific internal combustion and dynamic behavior of the engine.